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Almost all of Ameren’s revenues are subject to state or federal regulation

RATES AND REGULATION Rates The rates that Ameren Missouri, Ameren Illinois, and ATXI are allowed to charge for their utility services significantly influence the results of operations, financial position, and liquidity of these companies and Ameren

regulations, interpretations, amendments, or technical corrections to, or in connection with the OBBBA and the IRA, including the effects of the OBBBA as it relates to construction timelines of solar, wind, and battery storage projects, along with the ability

The law includes certain provisions that affect the regulation of Ameren Missouri’s electric and natural gas businesses

Discussion and Analysis of Financial Condition and Results of Operations 38 Overview 39 Results of Operations 42 Liquidity and Capital Resources 57 Outlook 67 Regulatory Matters 73 Accounting Matters 73

Business 7 General 7 Business Segments 7 Rates and Regulation 8 Transmission 10 Supply of Electric Power 10 Power Generation 12 Renewable Energy and Zero Emission Standards 13 Customer Energy-Efficiency Programs 14 Natural Gas Supply for Distribution 15 Human Capital Management 15 Industry Issues 17 Operating

Ameren Corporation, Ameren Missouri, and Ameren Illinois did not purchase equity securities reportable under Item 703 of Regulation S-K during the period from January 1, 2026, to March 31, 2026

The law includes certain provisions that affect the regulation of Ameren Missouri’s electric and natural gas businesses

Ameren Corporation, Ameren Missouri, and Ameren Illinois did not purchase equity securities reportable under Item 703 of Regulation S-K during the period from January 1, 2026, to March 31, 2026

Business 7 General 7 Business Segments 7 Rates and Regulation 8 Transmission 10 Supply of Electric Power 10 Power Generation 12 Renewable Energy and Zero Emission Standards 13 Customer Energy-Efficiency Programs 14 Natural Gas Supply for Distribution 15 Human Capital Management 15 Industry Issues 17 Operating

Discussion and Analysis of Financial Condition and Results of Operations 38 Overview 39 Results of Operations 42 Liquidity and Capital Resources 57 Outlook 67 Regulatory Matters 73 Accounting Matters 73

RATES AND REGULATION Rates The rates that Ameren Missouri, Ameren Illinois, and ATXI are allowed to charge for their utility services significantly influence the results of operations, financial position, and liquidity of these companies and Ameren

regulations, interpretations, amendments, or technical corrections to, or in connection with the OBBBA and the IRA, including the effects of the OBBBA as it relates to construction timelines of solar, wind, and battery storage projects, along with the ability

REGULATORY AND LEGISLATIVE RISKS We are subject to extensive regulation of our businesses

Almost all of Ameren’s revenues are subject to state or federal regulation

• the availability of fuel, materials and supplies, and equipment, and the potential disruptions in supply chains and inflationary pressures or tariffs on the prices and availability of commodities, labor, services, materials and supplies, and impacts associated with extended recovery periods from customers

• disruptions to the global supply chain as a result of shortages for labor, materials, or equipment, tariffs and international trade relations, geopolitical conflict, delivery delays, and economic pressures, among other things

to complete projects, which is dependent upon the availability of necessary materials and equipment, including those obligations that are affected by supply chain disruptions

ability of suppliers, contractors, and developers to meet contractual commitments and complete projects timely, which is dependent upon the availability of necessary labor, materials, and equipment, geopolitical conflict, or government actions, among other things

cost recovery mechanisms decreased revenues by $17 million, primarily due to lower bad debt costs on purchased receivables from alternative retail electric suppliers and environmental remediation revenues that are included in customer rates pursuant to their associated riders

• the availability of fuel, materials and supplies, and equipment, and the potential disruptions in supply chains and inflationary pressures or tariffs on the prices and availability of commodities, labor, services, materials and supplies, and impacts associated with extended recovery periods from customers

ability of suppliers, contractors, and developers to meet contractual commitments and complete projects timely, which is dependent upon the availability of necessary labor, materials, and equipment, geopolitical conflict, or government actions, among other things

• disruptions to the global supply chain as a result of shortages for labor, materials, or equipment, tariffs and international trade relations, geopolitical conflict, delivery delays, and economic pressures, among other things

cost recovery mechanisms decreased revenues by $17 million, primarily due to lower bad debt costs on purchased receivables from alternative retail electric suppliers and environmental remediation revenues that are included in customer rates pursuant to their associated riders

to complete projects, which is dependent upon the availability of necessary materials and equipment, including those obligations that are affected by supply chain disruptions

In 2026, Ameren Missouri executed electric service agreements with large load customers under its modified large primary service tariff that was approved in 2025, representing 2

The eligibility of standalone energy storage systems for rebates is subject to ICC approval, with the tariff filing due in the second half of 2026

costs, including but not limited to changes to tariffs on materials or government actions

These provisions create modifications to the PISA and integrated resource planning, require electric utilities to submit service tariff schedules for certain large load customers, allow the MoPSC to authorize inclusion of construction work in progress in rate base for new natural gas-fired generation facilities and new generation facilities approved through integrated resource planning

costs, including but not limited to changes to tariffs on materials or government actions

The eligibility of standalone energy storage systems for rebates is subject to ICC approval, with the tariff filing due in the second half of 2026

In 2026, Ameren Missouri executed electric service agreements with large load customers under its modified large primary service tariff that was approved in 2025, representing 2

These provisions create modifications to the PISA and integrated resource planning, require electric utilities to submit service tariff schedules for certain large load customers, allow the MoPSC to authorize inclusion of construction work in progress in rate base for new natural gas-fired generation facilities and new generation facilities approved through integrated resource planning

state, or local laws and other domestic or international governmental actions, including monetary, fiscal, foreign trade, and energy policies, foreign trade tariffs, executive orders, geopolitical developments, or extended federal government shutdowns or defunding

Our cash, cash equivalents, and restricted cash provided by operating activities is affected by fluctuations of trade accounts receivable, inventories, and accounts and wages payable, among other things, as well as the unique regulatory environment for each of our businesses. Substantially all expenditures related to fuel, purchased power, and natural gas purchased for resale are recovered from customers through rate adjustment mechanisms, which may be adjusted without a traditional regulatory rate review, sub

Cash Flows from Operating Activities Our cash provided by operating activities is affected by fluctuations of trade accounts receivable, inventories, and accounts and wages payable, among other things, as well as the unique regulatory environment for each of our businesses. Substantially all expenditures related to fuel, purchased power, and natural gas purchased for resale are recovered from customers through rate adjustment mechanisms, which may be adjusted without a traditional regulatory rate review, sub

earned under its MEEIA programs; • labor disputes, workforce reductions, our ability to attract and retain professional and skilled-craft employees, changes in future wage and employee benefits costs, including those resulting from changes in discount rates, mortality tables, medical cost trend rates, returns on benefit plan assets, and other assumptions; • the impact of negative opinions of us or our utility services that our customers, investors, legislators, regulators, creditors, rating agencies, or ot

between 1965 and 1980) 39% 39% 38% 41% Millennials (birth years between 1981 and 1996) 43% 43% 45% 41% Generation Z/Post Millennial (birth years after 1997) 9% 9% 9% 8% Collective bargaining units at Ameren’s subsidiaries consist of the International Brotherhood of Electrical Workers, the International Union of Operating Engineers, the Laborer’s International Union of North America, the United Association of Plumbers and Pipefitters, and 16 Table of Contents the United Government Security Officers of Ameri

its subsidiaries. AMEREN CORPORATION (Registrant) /s/ Leonard P. Singh Leonard P. Singh Executive Vice President and Chief Financial Officer (Principal Financial Officer) UNION ELECTRIC COMPANY (Registrant) /s/ Leonard P. Singh Leonard P. Singh Executive Vice President and Chief Financial Officer (Principal Financial Officer) AMEREN ILLINOIS COMPANY (Registrant) /s/ Leonard P. Singh Leonard P. Singh Executive Vice President and Chief Financial Officer (Principal Financial Officer) Date: May 7, 2026 67

Cash Flows from Operating Activities Our cash provided by operating activities is affected by fluctuations of trade accounts receivable, inventories, and accounts and wages payable, among other things, as well as the unique regulatory environment for each of our businesses. Substantially all expenditures related to fuel, purchased power, and natural gas purchased for resale are recovered from customers through rate adjustment mechanisms, which may be adjusted without a traditional regulatory rate review, sub

decoupled from sales volumes, which ensures that the electric distribution revenues authorized in a regulatory rate review are not affected by changes in sales volumes. POWER GENERATION Ameren Missouri owns energy centers that rely on a diverse fuel portfolio, including coal, nuclear, and natural gas, as well as renewable sources of generation. Both of Ameren Missouri’s coal-fired energy centers were constructed prior to 1978. As of December 31, 2025, Ameren Missouri’s coal-fired energy centers represented

business, as well as removal costs, net of salvage. Ameren Missouri continually reviews its generation portfolio and expected power needs, including estimates of future load growth. As a result, Ameren Missouri could modify its plan for generation capacity, the type of generation asset technology that will be employed, and whether capacity or power may be purchased, among other changes. Additionally, we continually review the reliability of our transmission and distribution systems, expected capacity needs, an

Item 1. Business 7 General 7 Business Segments 7 Rates and Regulation 8 Transmission 10 Supply of Electric Power 10 Power Generation 12 Renewable Energy and Zero Emission Standards 13 Customer Energy-Efficiency Programs 14 Natural Gas Supply for Distribution 15 Human Capital Management 15 Industry Issues 17 Operating Statistics 19 Available Information 21

these goals also relies on continuing to pursue a diverse portfolio, including low-carbon and carbon-free resources and energy-efficiency resources, while still meeting load growth opportunities; continuing to participate in efforts to help advance the development of technologies such as carbon capture and sequestration; the use of hydrogen fuel for electric production and energy storage, next generation nuclear, and large-scale long-cycle battery storage; and constructively engaging with legislators, regulato

other entities in various industries are considering either locating or expanding their operations within Ameren Missouri’s service territory. In order to address these load growth opportunities and ensure reliability, Ameren Missouri filed a notice of change in its September 2023 preferred resource plan with the MoPSC in 2025. Ameren is continuing to target net-zero carbon emissions by 2045, as well as a 60% reduction by 2030 and an 85% reduction by 2040 based on 2005 levels in a safe, reliable, and affordabl

MoPSC’s authority to require future proceedings if an event or circumstance occurs that significantly affects Ameren Missouri’s position in the MISO. Ameren Illinois’ election to participate in the MISO is subject to the ICC’s oversight. The CRGA requires the ICC and IPA to conduct a study to examine the costs and benefits of establishing a single, state-specific RTO, consolidating Illinois utilities’ RTO membership into one existing RTO, or maintaining the existing RTO membership structure. Additional s

15% of certain property, plant, and equipment placed in service, unless eligible for recovery under the RESRAM, remain subject to regulatory lag. As a result of the PISA election, additional provisions of the law apply to Ameren Missouri, including limitations on electric customer rate increases caused by the inclusion of incremental PISA deferrals in the revenue requirement. Pursuant to the PPRA discussed above, Ameren Missouri’s PISA election was extended through 2035 and an additional extension through 204

15% of certain property, plant, and equipment placed in service, unless eligible for recovery under the RESRAM, remain subject to regulatory lag. As a result of the PISA election, additional provisions of the law apply to Ameren Missouri, including limitations on electric customer rate increases caused by the inclusion of incremental PISA deferrals in the revenue requirement. Pursuant to the PPRA discussed above, Ameren Missouri’s PISA election was extended through 2035 and an additional extension through 204

under the reconciliation cap limit would adversely affect Ameren’s and Ameren Illinois’ results of operations, financial position, and liquidity. As a result of the election to use the PISA, Ameren Missouri’s electric service business is subject to a limitation on increasing the annual revenue requirement due to the inclusion of incremental PISA deferrals in the revenue requirement. Pursuant to the PPRA, Ameren Missouri’s PISA election was extended through 2035 and an additional extension through 2040

our allowed ROEs, within frameworks established by our regulators, while maintaining affordability for our customers; • the effect and duration of Ameren Illinois’ election to utilize MYRPs for electric distribution service ratemaking effective for rates beginning in 2024, including the effect of the reconciliation cap on the electric distribution revenue requirement; • the effect on Ameren Missouri of any customer rate caps or limitations on increasing the electric service revenue requirement pursuant

the recovery period of those costs. Additionally, the seasonality of our electric and natural gas businesses, primarily caused by seasonal customer rates and changes in customer demand due to weather, significantly affects the amount and timing of our cash provided by operating activities. For additional information on cash, cash equivalents, and restricted cash, see Note 13 – Supplemental Information under Part I, Item 1, of this report. Ameren Ameren’s cash provided by operating activities decreased $10

the recovery period of those costs. Additionally, the seasonality of our electric and natural gas businesses, primarily caused by seasonal customer rates and changes in customer demand due to weather, significantly affects the amount and timing of our cash provided by operating activities. See Note 2 – Rate and Regulatory Matters under Part II, Item 8, of this report for more information about our regulatory frameworks. Ameren Ameren’s cash provided by operating activities increased $590 million in 2025, c

natural gas and energy prices; operational performance of low- to zero-carbon resources; new transmission infrastructure; the ability to maintain system reliability; customer demand for energy including carbon-free energy; and constructive energy and economic policies, including those that address investment in energy infrastructure, global climate-related risks, incentives for clean energy technologies, and environmental regulations. Additional factors associated with operational risks for the construction

In addition, volatility in stock prices of perceived significant energy consumers, such as technology companies involved with artificial intelligence or cryptocurrency, or other significant developments with such companies, could cause increased volatility in stock prices of energy utility companies such as Ameren

guidance; • the effects of strategic initiatives, including mergers, acquisitions, divestitures, and reorganizations; • legal and administrative proceedings; • pandemics or other significant global health events, and their impacts on our results of operations, financial position, and liquidity; and • the impacts of global conflicts and related sanctions imposed by the United States and other governments, including potential impacts on the cost and availability of fuel, natural gas, enriched uranium

revenues at Ameren Missouri, pursuant to the April 2025 MoPSC electric rate order, effective June 1, 2025, partially offset by higher depreciation and amortization and interest expenses in base rates (8 cents per share); • a higher allowance for equity funds used during construction and increased base rate revenues at Ameren Missouri for the inclusion of previously deferred interest charges under PISA pursuant to the April 2025 MoPSC electric rate order, partially offset by lower interest deferrals associat

Illinois Transmission Interest charges increased by $8 million, p rimarily because of issuances of long-term debt in March and September 2025 and June 2024, which increased interest expense by $14 million

are compared with current commodity prices; • market values of natural gas that differ from the cost of this commodity in inventory; • actual cash outlays for interest expense and the purchase of commodities that differ from anticipated cash outlays; and • actual off-system sales revenues that differ from anticipated revenues. The derivatives that we use to hedge these risks are governed by our risk management policies for forward contracts, futures, options, and swaps. Our net positions are contin

Additionally, fluctuations in interest rates and conditions in the capital and credit markets affect our cost of borrowing, our pension and postretirement benefits costs, the cash surrender value of COLI, and the asset value of Ameren Missouri’s nuclear decommissioning trust fund

Net income was unfavorably affected in 2025 compared with 2024 by increased financing costs, primarily resulting from higher interest rates on higher debt balances at Ameren Missouri and Ameren (parent) and by increased other operations and maintenance expenses not subject to formula rates, riders, or trackers, excluding a charge related to the NSR and Clean Air Act litigation, prim

and capital market conditions, including foreign trade tariffs or trade wars, evolving federal regulatory priorities, and the impact of such conditions on interest rates, inflation, commodity prices, and investments

changes in interest rates, income taxes, taxes other than income taxes, pension and other post-retirement benefits costs, and amortization of certain assets

Net income was unfavorably affected in 2025 compared with 2024 by increased financing costs, primarily resulting from higher interest rates on higher debt balances at Ameren Missouri and Ameren (parent) and by increased other operations and maintenance expenses not subject to formula rates, riders, or trackers, excluding a charge related to the NSR and Clean Air Act litigation, prim

and capital market conditions, including foreign trade tariffs or trade wars, evolving federal regulatory priorities, and the impact of such conditions on interest rates, inflation, commodity prices, and investments

Additionally, fluctuations in interest rates and conditions in the capital and credit markets affect our cost of borrowing, our pension and postretirement benefits costs, the cash surrender value of COLI, and the asset value of Ameren Missouri’s nuclear decommissioning trust fund

Beginning June 2026, the CRGA will increase the amount of customer collections by adding an annual inflation adjustment to the $4

changes in interest rates, income taxes, taxes other than income taxes, pension and other post-retirement benefits costs, and amortization of certain assets

8 Transmission 10 Supply of Electric Power 10 Power Generation 12 Renewable Energy and Zero Emission Standards 13 Customer Energy-Efficiency Programs 14 Natural Gas Supply for Distribution 15 Human Capital Management 15 Industry Issues 17 Operating Statistics 19 Available Information 21

reconciliation adjustment review filed with the ICC in April 2026, Ameren Illinois’ January 2026 appeal of the November 2025 ICC order issued in the 2025 natural gas delivery service rate review, Ameren Illinois’ 2020 QIP reconciliation hearing, and the January and April 2025 appeals of FERC’s October 2024 and March 2025 orders by the MISO transmission owners, including Ameren Missouri, Ameren Illinois, and

regulatory frameworks, some of which are more specifically identified in the following risk factors, regulate, among other matters, the electric and natural gas utility industries

• Ameren Missouri operates a rate-regulated electric generation, transmission, and distribution business and a rate-regulated natural gas distribution business in Missouri

• Ameren Missouri operates a rate-regulated electric generation, transmission, and distribution business and a rate-regulated natural gas distribution business in Missouri

• Ameren Missouri operates a rate-regulated electric generation, transmission, and distribution business and a rate-regulated natural gas distribution business in Missouri

reconciliation adjustment review filed with the ICC in April 2026, Ameren Illinois’ January 2026 appeal of the November 2025 ICC order issued in the 2025 natural gas delivery service rate review, Ameren Illinois’ 2020 QIP reconciliation hearing, and the January and April 2025 appeals of FERC’s October 2024 and March 2025 orders by the MISO transmission owners, including Ameren Missouri, Ameren Illinois, and

• Ameren Missouri operates a rate-regulated electric generation, transmission, and distribution business and a rate-regulated natural gas distribution business in Missouri

regulatory frameworks, some of which are more specifically identified in the following risk factors, regulate, among other matters, the electric and natural gas utility industries

• Ameren Missouri operates a rate-regulated electric generation, transmission, and distribution business and a rate-regulated natural gas distribution business in Missouri

• Ameren Missouri operates a rate-regulated electric generation, transmission, and distribution business and a rate-regulated natural gas distribution business in Missouri

8 Transmission 10 Supply of Electric Power 10 Power Generation 12 Renewable Energy and Zero Emission Standards 13 Customer Energy-Efficiency Programs 14 Natural Gas Supply for Distribution 15 Human Capital Management 15 Industry Issues 17 Operating Statistics 19 Available Information 21

to obtain sufficient insurance at a reasonable cost, or, in the absence of insurance, the ability to timely recover uninsured losses from our customers; • the impact of cyberattacks and data security risks on us, our suppliers, or other entities on the grid, including those arising from generative or agentic artificial intelligence, which could, among other things, result in the loss of operational control of energy centers and electric and natural gas transmission and distribution systems and/or the loss of d

As owners and operators of bulk power transmission systems and electric energy centers, we are subject to mandatory NERC reliability standards, including cybersecurity standards

Ameren Missouri, Ameren Illinois, and ATXI are also subject to mandatory reliability standards, including cybersecurity standards adopted by the FERC, to ensure the reliability of the bulk electric power system

19 Table of Contents Electric Operating Statistics – Year Ended December 31, 2025 2024 2023 Ameren Missouri fuel costs (cents per kilowatthour generated) (a) 1

19 Table of Contents Electric Operating Statistics – Year Ended December 31, 2025 2024 2023 Ameren Missouri fuel costs (cents per kilowatthour generated) (a) 1

• limited availability of fuel supply and our reliance on licensed fuel assemblies from primarily one NRC-licensed supplier of Callaway Energy Center’s assemblies

economy, including in the transportation sector. In addition, several entities in various industries, including data center, healthcare, manufacturing, distribution, warehousing, alternative energy, fabrication, and food production, are considering either locating or expanding their operations within our service territories. In 2026, Ameren Missouri executed electric service agreements with large load customers under its modified large primary service tariff that was approved in 2025, representing 2.8 gigawatts

economy, including in the transportation sector. In addition, several entities in various industries, including data center, healthcare, manufacturing, distribution, warehousing, alternative energy, fabrication, and food production, are considering either locating or expanding their operations within our service territories. In February 2026, Ameren Missouri executed electric service agreements with large load customers under the modified tariff as discussed above, representing 2.2 gigawatts of demand. Construc

$ 350 million of 3.65 % senior unsecured notes that matured in February 2026. Ameren Missouri In February 2026, Ameren Missouri issued $ 450 million of 4.80 % first mortgage bonds due March 2036 and $ 450 million of 5.55 % first mortgage bonds due March 2056. Interest is payable semiannually for both issuances on March 15 and September 15 of each year, beginning September 15, 2026. Net proceeds from the February 2026 issuances were used for capital expenditures and to repay short-term debt. Ameren Missouri

services resulting from customer growth patterns or usage, including demand from data centers, technological advances, including advances in customer energy efficiency, electric vehicles, electrification of various industries, energy storage, and private generation sources, which are becoming increasingly cost-competitive; • Ameren Missouri’s ability to earn, utilize, or transfer at a reasonable price federal production and investment tax credits related to renewable energy projects and nuclear energy prod

to the transfer of production and investment tax credits to unrelated parties. • A $27 million increase due to the timing of payments for spent nuclear fuel storage and reimbursements from the DOE. • A $24 million increase due to the timing of payments for accounts payable. 58 Table of Contents The following items partially offset the increase in Ameren’s cash from operating activities between periods: • A $144 million increase in interest payments, primarily due to higher average outstanding debt and in

In addition, several entities in various industries, including data center, healthcare, manufacturing, distribution, warehousing, alternative energy, fabrication, and food production, are considering either locating or expanding their operations within our service territories

risks, cyber attacks, including ransomware and other ransom-based attacks and those attacks arising from or generated by generative or agentic artificial intelligence, hacking, social engineering, and other forms of malicious cybersecurity and/or privacy events, which could result in the loss of operational control of energy centers and electric and natural gas transmission and distribution systems a

In addition, several entities in various industries, including data center, healthcare, manufacturing, distribution, warehousing, alternative energy, fabrication, and food production, are considering either locating or expanding their operations within our service territories

implement or maintain information systems

• the impact of cyberattacks and data security risks on us, our suppliers, or other entities on the grid, including those arising from generative or agentic artificial intelligence, which could, among other things, result in the loss of operational control of energy centers and electric and natural gas transmission and distribution systems and/or the loss of data, such as customer, employee, financial, and operati

domestic or international governmental actions, including monetary, fiscal, foreign trade, and energy policies, foreign trade tariffs, executive orders, geopolitical developments, or extended federal government shutdowns or defunding

to meet contractual commitments and complete projects timely, which is dependent upon the availability of necessary labor, materials, and equipment, geopolitical conflict, or government actions, among other things

Ameren Illinois, or ATXI is found not to be in compliance with these mandatory reliability standards, it could incur substantial monetary penalties and other sanctions

conflict and other events beyond our control, including delays arising from government shutdowns or construction delays due to weather

to meet contractual commitments and complete projects timely, which is dependent upon the availability of necessary labor, materials, and equipment, geopolitical conflict, or government actions, among other things